The present invention relates to fluid handling systems and, more particularly, to so-called "quick coupling" connectors which are manually manipulated to effect connection or disconnection.
Fluid handling systems, particularly those using flexible tubing or hose in sizes 3/4 inch to 11/2 inch I.D., typically include joints made with barbed connectors and hose secured with mechanical clamps such as worm type or deformable metal bands. These type of joints present problems for manufacturers who must maintain efficient, high volume production at the least cost, such as in the marine, appliance and specialized vehicle markets, including mobile washers and sprayers, as well as agricultural fertilizing and irrigation, to name a few. These joints can also be very difficult to service in the field if the joint is difficult to access with the necessary tool to remove the mechanical clamp.
For example, many recreational fishing boat manufacturers feature livewell/baitwell systems in their upper and mid-level boats. These systems typically use barbed fittings to connect hoses with various components, such as pumps, valves, aerator heads, thru-hull fittings, drain fittings, overflow fittings and the like. There may be two dozen or more hose connections in a single boat. Production line installation of these systems is time consuming, as each hose connection requires a clamp, typically a stainless steel worm type, which must be carefully positioned and properly tightened to assure a leak-tight joint. These clamps can be difficult to install in tight quarters, often typical of boat bilge areas, where much of the livewell system is located. Boat manufacturers leak test the system after installation and are often confronted with leaks at the hose connections. However, once installed, these systems are often covered by gas tanks and decking making access for service difficult, particularly if a tool, such as a screwdriver, must be used to remove the mechanical clamp. To partially solve this problem, many boat manufacturers have added the step of coating the barbed connector with silicone sealant before assembling the hose, in an effort to minimize the occurence of leaking hose joints. The silicone sealant, applied using a caulking gun type applicator, is sometimes used in excess which can restrict or completely block the opening in the hose or connector, a problem often not found until the boat is in service. Thus, boat manufacturers have had a long felt need for a system which would allow fast, reliable hose connections to be made on the production line and which would, in turn, reduce the number and duration of field repairs.
One of the important requirements for an improved hose connection system is that it must function with the standard hose that is currently used by boat manufacturers to plumb their livewell and bilge pump systems. This hose, which is widely available from a number of producers, is manufactured by co-extruding flexible PVC with a helical coil of rigid plastic integral within the hose wall. The resulting hose can accommodate a small radius bend without collapsing, yet is pliable so it can be easily routed around obstacles. The problem with this hose is that its outer wall is not smooth. The integral helical coil creates an outer surface unsuitable for sealing using an o-ring.
Another important requirement for an improved hose connection system is that it must be adaptable to existing barbed type fittings because not all system components may be readily changed. System components may be sourced from several manufacturers, so a new standard is not readily implementable.
Any improved hose connection system must not be so bulky as to cause interference with adjacent structure.
An improved hose connection system must be simple and inexpensive, and therefore practical for use on all system joints.
A review of available prior art quick coupling systems shows that none is suitable to meet these requirements. There is nothing that would allow existing barbed fittings to be quickly adapted to serve as quick coupling fittings and eliminate mechanical clamps. Also, there are no quick couplings that are both functional and simple enough to produce at a cost low enough to be widely used in volume production applications, such as those described above.
One available quick coupling is the push-to-connect type where a socket and retaining collet are incorporated onto the fluid system component to which the hose is to be attached. The hose is simply pushed into the socket to form a leak-tight, positively retained connection. Invariably, this type of quick coupling uses an o-ring seal between the inside wall of an outer sleeve and the outside wall surface of the tube. A reliable seal requires a tube with a smooth outer wall. In addition, the tubing must be sufficiently stiff to maintain contact with the o-ring without collapsing or distorting under the o-ring compression loading or under the tube stresses created if the tubing is bent abruptly at the connector exit plane. For reasons cited above, standard marine hose does not have either the smooth wall or the stiffness characteristics which would allow push-to-connect type of quick couplings to be used satisfactorily. In addition, push-to-connect quick couplings would be too expensive to incorporate on all of the different types of fluid system fittings and components used, and no fitting exists which would readily convert a barbed connector to a quick coupling fitting.
Other types of prior art quick couplings typically use a male insert portion which includes an o-ring seal member and a female socket portion which includes a smooth bore into which the male portion is inserted, creating a leak-tight seal. A locking and quick release latch system is generally incorporated into the female socket portion. These are the basic components of the subject quick coupling system also, but the special needs of the markets addressed, require novel features not heretofore available.